DC step-down multi-cell lithium battery charger

DC step-down multi-cell lithium battery charger, the input voltage can be up to 32V, the charging current is about 2A for a single battery per channel, the circuit consists of two parts, the 32V DC input voltage is stepped down to 5V by XL4015, the charging part uses four channels IP5306, this chip is a special chip for power banks. We only use the charging part of it, which is better because it is cheaper. The circuit is as follows: DC to 5V. The voltage must not exceed 5V during debugging. If it exceeds it, it will easily burn the IP5306 chip, R5 and R6. It doesn't need to be welded, it is just used to adjust the voltage when the output 5V voltage is too low.

The picture below shows the IP5306 charging circuit. Two lights are used to indicate charging. D1, D3, D5, and D7 will flash during charging and stay on after full charge. D2, D4, D6, and D8 will flash when the battery voltage is lower than 2.75V. The path is the same:

 PCB empty board: Reverse side:      Front side:      After soldering PCB:     After the first version was made, after the soldering test, it was found that when the battery was installed in the battery box and the charging output was unplugged, the ip5306 would burn from time to time, and 5 ICs were burned continuously. After carefully modifying the circuit according to the PDF standard, after testing it 50 times after installing the battery and unplugging the charging input, the charging IC no longer burned. The circuit has been nearly corrected. The board is the first version. I cut off several circuits with a knife and soldered the newly added components to test them. No problem of burning the chip!

The picture below is the modified temporary debugging PCB:         Test video link: http://v.youku.com/v_show/id_XNDQ2NTM3MDYxMg==.html?x&sharefrom=android&sharekey=c640ffe0d1e4cdf481aba013cbac7ea22